so the zetsu said you can do anything you want in the land of dreams, even revive the dead, so im guessing he only agreed to the plan after rin died, so he can go to the land of dreams and revive rin
but in the end i think kakashi or naruto will get through to obito and he will try to back out of the plan
but in the end i think kakashi or naruto will get through to obito and he will try to back out of the plan